How do you get paint to stick to fillers?
If it's just ordinary filler you can pop some acrylic primer/undercoat on it before painting. I always do this on any filler as it can flash through the emulsion.
Why is my paint not covering filler?
Make sure that all filled areas are rubbed down smooth and level. You will need to prime the filler before painting to prevent subsequent coats being absorbed more rapidly than on other areas.
Can you paint directly on filler?
If you are using a wall filler brand like Tetrion or Everbuild, you will have to let the filler dry for two hours before it's dry to the touch, and if you wish to paint over it, you will have to let it dry for 24 hours.
What do you do when paint won't stick?
You are more than likely painting over a shiny,slippery or dirty surface. To promote adhesion use a primer after cleaning your walls. This will solve your problem unless something unusual is going on.
Do I need to prime filler before painting?
What are the red flags after fillers?
Can filler react with paint?
Why I stopped using fillers?